Variable-rate application of fertiliser – A tool for improving farm systems and environmental performance?

Abstract

Nitrogenous fertilisers – especially urea – are key inputs into many farming systems. In New Zealand, increasing restrictions on nitrogen application on pastures means there is an urgent need to ensure that it is used effectively. One technology that has been developed that may contribute to this challenge is variable-rate application (VRA) of fertiliser. This trial used VRA technology to apply N fertiliser as a function of the pasture mass present at the time of application. The effect of VRA of N fertiliser on pasture production on five farms over one season was examined, and the impact of those changes on farm system metrics, including environmental performance, was estimated. Averaged over all five farms, there was no statistically significant difference between VRA and blanket-rate application of fertiliser on pasture production. However, one farm did show a significant difference. Although the absolute difference was small, this suggested that VRA could be a useful tool in addressing the challenge of driving better farm performance with reduced environmental impact.